The present invention relates generally to insertable and removable typewriter ribbon cartridges of the type disclosed in U.S. Pat. No. 3,643,777 entitled TYPEWRITER RIBBON CARTRIDGE granted on Feb. 22, 1972 and United States Patent Application Ser. No. 150,946 filed June 9, 1971 entitled TYPEWRITER RIBBON CARTRIDGE both of which are assigned to the assignee of the instant application. The present invention cooperates with a typewriter borne mechanism that is clearly described in co-pending United States Patent Application entitled AUTOMATIC FUNCTION MECHANISM FOR TYPEWRITERS filed simultaneously with the instant application with Stanley J. Klem as sole inventor and assigned to the same assignee. The invention in its broadest aspects is not restricted to this ribbon cartridge structure, but has been illustrated and described for explanatory purposes and could readily be adapted to other ribbon cartridge structures. The ribbon cartridge of the present invention may include an error correction ribbon disposed therein whereby the correction ribbon is guided from the correction ribbon cartridge supply chamber along an integral ribbon guide arm that extends from the correction ribbon cartridge supply chamber to the typewriter print station. More specifically, the present invention is concerned with a modified ribbon cartridge construction that includes a pivotal abutment thereon to engage a backspace coupled responsive member thereby actuating the backspace mechanism to reposition the typewriter carriage to the proper print station.
When it is desired to correct an error, a printing ribbon cartridge is removed from the typewriter and the modified ribbon cartridge is inserted. During insertion, the cartridge borne pivotal abutment engages the backspace coupled responsive member. However, no actuation of the backspace mechanism takes place since the pivotal abutment on the modified ribbon cartridge pivots clear of the responsive member until the abutment is inserted beyond the responsive member. The pivotal abutment is then biased to return to its actuable state. After the error is corrected, the modified ribbon cartridge is removed from the typewriter. As the modified ribbon cartridge is removed, the pivotal abutment now prevented from pivoting, engages the backspace coupled responsive member and actuates the backspace mechanism to reposition the typewriter carriage to the proper print station where the correct character is typed.
The correction of errors in typewriters as disclosed in the prior art required a series of sequential manually manipulative operations so that the carriage of the typewriter may be backspaced a plurality of times to correct the error. For example, when an operator typed an erroneous character, it first became necessary to manually depress the backspace key thereby actuating the backspace mechanism to reposition the typewriter carriage to the proper print station for making the correction. After the erroneous typed character is removed by striking over the character through the correction ribbon, the backspace key was again manually depressed to actuate the backspace mechanism a second time. The typewriter carriage is repositioned to the proper printing station a second time and then the correct character is typed. Therefore, a series of manually manipulative operations by the operator were necessary to correct an erroneously typed character. The end result of the foregoing disadvantages of the prior art is that the typing speed is significantly reduced, total typing time is increased and the possibility of compounding the error by inadvertent multiple backspacing is increased.
The present invention overcomes the obvious disadvantages of the prior art in that the manual manipulation required to actuate the backspace mechanism and reposition the typewriter carriage to the proper print station after an error correction operation is reduced just by inserting and removing the ribbon cartridge.